The invention arose during continuing development efforts related to commonly owned copending application Ser. No. 07/389,346, filed Aug. 3, 1989.
The present invention relates to continuing development efforts directed toward manufacturing methods and facilities for applying a coating to vehicle structural components, including the application of a hot melt wax coating to vehicle frames for protection against rust and corrosion.
The invention of the noted copending application arose during development efforts directed toward reducing the high capital expense of a manufacturing facility for coating vehicle structural components such as frames. Vehicle manufacturers are more commonly requiring vendors and parts suppliers to have local on-site manufacturing or processing facilities coordinating with the assembly operation of the vehicle manufacturer. In the case of suppliers providing vehicle structural components such as frames, this requires erection of a coating facility at each of the various satellite assembly facilities. However, erection of multiple satellite coating facilities is not cost effective due to the extremely high capital expense of same.
A vehicle frame is a generally flat longitudinal structural member which in one exemplary size has a longitudinal length of about 178 inches, a lateral width of about 42 inches, and a height of about 16 inches, though the dimensions may of course vary. Prior facilities for applying a hot melt wax coating to such frames typically require buildings of about 2 million cubic feet, with 50,000 square feet of lateral area and over 60 feet in height. The frames are hung vertically and transported to a dipping tank and dipped downwardly into the tank for coating the frame in the hot melt wax liquid, and then raised out of the tank. Hence, the building must be at least twice as high as the longitudinal length of the frame. The tank volume is about 63,000 gallons. The building is heated by ovens or the like such that the heated air in the building preheats the frames prior to dipping, to enhance the coating during the dip into the hot melt wax liquid tank. Preheating of the frames with air is inefficient and requires long preheat times. The vertical hanging of the frames also requires large openings into and out of the building, causing significant heat loss and energy inefficiency. The construction cost of the building is high because of its special requirements. Furthermore, the building has no other use.
The invention of the copending application addresses and solves the above noted problems with a simple and effective manufacturing method and facility. The invention of the copending application reduces the building volume by a factor of 10 or more, e.g. the new building can be reduced to as little as 5% of the volume of the prior building. The invention of the copending application also reduces the tank volume requirements for the coating liquid to as little as 4%, e.g. to as low as 2,000 gallons instead of the 63,000 gallons required for the above noted prior tank. This saves wax cost. The invention of the copending application also significantly reduces the height requirement of the tank, e.g. from about 25 feet deep to about 25 inches deep. This desirably solves problems of hydrostatic fluid pressure and leakage caused thereby at the bottom of the tank. The construction cost of the building is reduced by a factor of about 10 due to the reduced special requirements of the building and also due to reduced loading capability of the building due to special transport structure within the building in accordance with the invention for carrying the vehicle structural components. The building is adaptable to other uses in the event of changing requirements. The transport mechanism and core within the building can be moved to other buildings and locations.
The present invention provides a manufacturing method and facility with substantially reduced space requirements. The present invention coats the frames by dipping them in a generally vertical position and transports the frames horizontally through a narrow perimeter tank formed in the space between concentric tank walls. In one embodiment, the frames are hung vertically on a cylinder which rotates to move the frames to various positions around the perimeter of the cylinder.